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904 / 727 automatic transmission harsh or soft shift
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Author:  steve93101 [ Sun Sep 29, 2019 7:29 pm ]
Post subject:  904 / 727 automatic transmission harsh or soft shift

1965 Valiant

Ten years after a transmission rebuild I finally undertook to address a hard 1-2 shift at slow speed / light throttle.
The thing worked fine but on soft acceleration from dead stop it would always shift with a hard clunk.

There is a threaded rod that attaches to the carb linkage and goes down to the trans, co-ordinates the throttle position with the trans fluid pressure & shift points. Apply some liquid wrench to the threads and simply pull / pop out the ball from the socket ( held in by a spring clip). Other years & set ups use a cable vs a threaded ride; not sure how the cable adjust but result should be the same.

-If the trans seems to up-shift slow & harsh there is probably too much pressure ; shorten the linkage ....a little goes a long ways.

I did three turns of the buckle and it was perfect... vast improvement. Still a firm shift but not a jarring clunk. Don't make it too short , to the point where the shift is too soft and you are slipping & chewing up bands

-If the trans up-shift is too fast, there may not be enough pressure on the kick down lever, you may need to lengthen the linkage.

Imagine... after 10 years; 20 minutes of web search and 10 minutes of shade tree mechanic work time; short test ride and it was Miller Time !

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